1 /* $OpenBSD: sshd.c,v 1.506 2018/03/03 03:15:51 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 __RCSID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 #include <sys/ioctl.h> 50 #include <sys/mman.h> 51 #include <sys/socket.h> 52 #ifdef HAVE_SYS_STAT_H 53 # include <sys/stat.h> 54 #endif 55 #ifdef HAVE_SYS_TIME_H 56 # include <sys/time.h> 57 #endif 58 #include "openbsd-compat/sys-tree.h" 59 #include "openbsd-compat/sys-queue.h" 60 #include <sys/wait.h> 61 62 #include <errno.h> 63 #include <fcntl.h> 64 #include <netdb.h> 65 #ifdef HAVE_PATHS_H 66 #include <paths.h> 67 #endif 68 #include <grp.h> 69 #include <pwd.h> 70 #include <signal.h> 71 #include <stdarg.h> 72 #include <stdio.h> 73 #include <stdlib.h> 74 #include <string.h> 75 #include <unistd.h> 76 #include <limits.h> 77 78 #ifdef WITH_OPENSSL 79 #include <openssl/dh.h> 80 #include <openssl/bn.h> 81 #include <openssl/rand.h> 82 #include "openbsd-compat/openssl-compat.h" 83 #endif 84 85 #ifdef HAVE_SECUREWARE 86 #include <sys/security.h> 87 #include <prot.h> 88 #endif 89 90 #ifdef __FreeBSD__ 91 #include <resolv.h> 92 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 93 #include <gssapi/gssapi.h> 94 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 95 #include <gssapi.h> 96 #endif 97 #endif 98 99 #include "xmalloc.h" 100 #include "ssh.h" 101 #include "ssh2.h" 102 #include "sshpty.h" 103 #include "packet.h" 104 #include "log.h" 105 #include "buffer.h" 106 #include "misc.h" 107 #include "match.h" 108 #include "servconf.h" 109 #include "uidswap.h" 110 #include "compat.h" 111 #include "cipher.h" 112 #include "digest.h" 113 #include "key.h" 114 #include "kex.h" 115 #include "myproposal.h" 116 #include "authfile.h" 117 #include "pathnames.h" 118 #include "atomicio.h" 119 #include "canohost.h" 120 #include "hostfile.h" 121 #include "auth.h" 122 #include "authfd.h" 123 #include "msg.h" 124 #include "dispatch.h" 125 #include "channels.h" 126 #include "session.h" 127 #include "monitor.h" 128 #ifdef GSSAPI 129 #include "ssh-gss.h" 130 #endif 131 #include "monitor_wrap.h" 132 #include "ssh-sandbox.h" 133 #include "auth-options.h" 134 #include "version.h" 135 #include "ssherr.h" 136 #include "blacklist_client.h" 137 138 #ifdef LIBWRAP 139 #include <tcpd.h> 140 #include <syslog.h> 141 int allow_severity; 142 int deny_severity; 143 #endif /* LIBWRAP */ 144 145 /* Re-exec fds */ 146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 150 151 extern char *__progname; 152 153 /* Server configuration options. */ 154 ServerOptions options; 155 156 /* Name of the server configuration file. */ 157 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 158 159 /* 160 * Debug mode flag. This can be set on the command line. If debug 161 * mode is enabled, extra debugging output will be sent to the system 162 * log, the daemon will not go to background, and will exit after processing 163 * the first connection. 164 */ 165 int debug_flag = 0; 166 167 /* 168 * Indicating that the daemon should only test the configuration and keys. 169 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 170 * configuration, optionally using connection information provided by the 171 * "-C" flag. 172 */ 173 int test_flag = 0; 174 175 /* Flag indicating that the daemon is being started from inetd. */ 176 int inetd_flag = 0; 177 178 /* Flag indicating that sshd should not detach and become a daemon. */ 179 int no_daemon_flag = 0; 180 181 /* debug goes to stderr unless inetd_flag is set */ 182 int log_stderr = 0; 183 184 /* Saved arguments to main(). */ 185 char **saved_argv; 186 int saved_argc; 187 188 /* re-exec */ 189 int rexeced_flag = 0; 190 int rexec_flag = 1; 191 int rexec_argc = 0; 192 char **rexec_argv; 193 194 /* 195 * The sockets that the server is listening; this is used in the SIGHUP 196 * signal handler. 197 */ 198 #define MAX_LISTEN_SOCKS 16 199 int listen_socks[MAX_LISTEN_SOCKS]; 200 int num_listen_socks = 0; 201 202 /* 203 * the client's version string, passed by sshd2 in compat mode. if != NULL, 204 * sshd will skip the version-number exchange 205 */ 206 char *client_version_string = NULL; 207 char *server_version_string = NULL; 208 209 /* Daemon's agent connection */ 210 int auth_sock = -1; 211 int have_agent = 0; 212 213 /* 214 * Any really sensitive data in the application is contained in this 215 * structure. The idea is that this structure could be locked into memory so 216 * that the pages do not get written into swap. However, there are some 217 * problems. The private key contains BIGNUMs, and we do not (in principle) 218 * have access to the internals of them, and locking just the structure is 219 * not very useful. Currently, memory locking is not implemented. 220 */ 221 struct { 222 struct sshkey **host_keys; /* all private host keys */ 223 struct sshkey **host_pubkeys; /* all public host keys */ 224 struct sshkey **host_certificates; /* all public host certificates */ 225 int have_ssh2_key; 226 } sensitive_data; 227 228 /* This is set to true when a signal is received. */ 229 static volatile sig_atomic_t received_sighup = 0; 230 static volatile sig_atomic_t received_sigterm = 0; 231 232 /* session identifier, used by RSA-auth */ 233 u_char session_id[16]; 234 235 /* same for ssh2 */ 236 u_char *session_id2 = NULL; 237 u_int session_id2_len = 0; 238 239 /* record remote hostname or ip */ 240 u_int utmp_len = HOST_NAME_MAX+1; 241 242 /* options.max_startup sized array of fd ints */ 243 int *startup_pipes = NULL; 244 int startup_pipe; /* in child */ 245 246 /* variables used for privilege separation */ 247 int use_privsep = -1; 248 struct monitor *pmonitor = NULL; 249 int privsep_is_preauth = 1; 250 static int privsep_chroot = 1; 251 252 /* global authentication context */ 253 Authctxt *the_authctxt = NULL; 254 255 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 256 struct sshauthopt *auth_opts = NULL; 257 258 /* sshd_config buffer */ 259 Buffer cfg; 260 261 /* message to be displayed after login */ 262 Buffer loginmsg; 263 264 /* Unprivileged user */ 265 struct passwd *privsep_pw = NULL; 266 267 /* Prototypes for various functions defined later in this file. */ 268 void destroy_sensitive_data(void); 269 void demote_sensitive_data(void); 270 static void do_ssh2_kex(void); 271 272 /* 273 * Close all listening sockets 274 */ 275 static void 276 close_listen_socks(void) 277 { 278 int i; 279 280 for (i = 0; i < num_listen_socks; i++) 281 close(listen_socks[i]); 282 num_listen_socks = -1; 283 } 284 285 static void 286 close_startup_pipes(void) 287 { 288 int i; 289 290 if (startup_pipes) 291 for (i = 0; i < options.max_startups; i++) 292 if (startup_pipes[i] != -1) 293 close(startup_pipes[i]); 294 } 295 296 /* 297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 298 * the effect is to reread the configuration file (and to regenerate 299 * the server key). 300 */ 301 302 /*ARGSUSED*/ 303 static void 304 sighup_handler(int sig) 305 { 306 int save_errno = errno; 307 308 received_sighup = 1; 309 errno = save_errno; 310 } 311 312 /* 313 * Called from the main program after receiving SIGHUP. 314 * Restarts the server. 315 */ 316 static void 317 sighup_restart(void) 318 { 319 logit("Received SIGHUP; restarting."); 320 if (options.pid_file != NULL) 321 unlink(options.pid_file); 322 platform_pre_restart(); 323 close_listen_socks(); 324 close_startup_pipes(); 325 alarm(0); /* alarm timer persists across exec */ 326 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 327 execv(saved_argv[0], saved_argv); 328 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 329 strerror(errno)); 330 exit(1); 331 } 332 333 /* 334 * Generic signal handler for terminating signals in the master daemon. 335 */ 336 /*ARGSUSED*/ 337 static void 338 sigterm_handler(int sig) 339 { 340 received_sigterm = sig; 341 } 342 343 /* 344 * SIGCHLD handler. This is called whenever a child dies. This will then 345 * reap any zombies left by exited children. 346 */ 347 /*ARGSUSED*/ 348 static void 349 main_sigchld_handler(int sig) 350 { 351 int save_errno = errno; 352 pid_t pid; 353 int status; 354 355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 356 (pid < 0 && errno == EINTR)) 357 ; 358 errno = save_errno; 359 } 360 361 /* 362 * Signal handler for the alarm after the login grace period has expired. 363 */ 364 /*ARGSUSED*/ 365 static void 366 grace_alarm_handler(int sig) 367 { 368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 369 kill(pmonitor->m_pid, SIGALRM); 370 371 /* 372 * Try to kill any processes that we have spawned, E.g. authorized 373 * keys command helpers. 374 */ 375 if (getpgid(0) == getpid()) { 376 signal(SIGTERM, SIG_IGN); 377 kill(0, SIGTERM); 378 } 379 380 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 381 382 /* Log error and exit. */ 383 sigdie("Timeout before authentication for %s port %d", 384 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 385 } 386 387 static void 388 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 389 { 390 u_int i; 391 int remote_major, remote_minor; 392 char *s; 393 char buf[256]; /* Must not be larger than remote_version. */ 394 char remote_version[256]; /* Must be at least as big as buf. */ 395 396 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n", 397 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION, 398 *options.version_addendum == '\0' ? "" : " ", 399 options.version_addendum); 400 401 /* Send our protocol version identification. */ 402 if (atomicio(vwrite, sock_out, server_version_string, 403 strlen(server_version_string)) 404 != strlen(server_version_string)) { 405 logit("Could not write ident string to %s port %d", 406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 407 cleanup_exit(255); 408 } 409 410 /* Read other sides version identification. */ 411 memset(buf, 0, sizeof(buf)); 412 for (i = 0; i < sizeof(buf) - 1; i++) { 413 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 414 logit("Did not receive identification string " 415 "from %s port %d", 416 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 417 cleanup_exit(255); 418 } 419 if (buf[i] == '\r') { 420 buf[i] = 0; 421 /* Kludge for F-Secure Macintosh < 1.0.2 */ 422 if (i == 12 && 423 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 424 break; 425 continue; 426 } 427 if (buf[i] == '\n') { 428 buf[i] = 0; 429 break; 430 } 431 } 432 buf[sizeof(buf) - 1] = 0; 433 client_version_string = xstrdup(buf); 434 435 /* 436 * Check that the versions match. In future this might accept 437 * several versions and set appropriate flags to handle them. 438 */ 439 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 440 &remote_major, &remote_minor, remote_version) != 3) { 441 s = "Protocol mismatch.\n"; 442 (void) atomicio(vwrite, sock_out, s, strlen(s)); 443 logit("Bad protocol version identification '%.100s' " 444 "from %s port %d", client_version_string, 445 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 446 close(sock_in); 447 close(sock_out); 448 cleanup_exit(255); 449 } 450 debug("Client protocol version %d.%d; client software version %.100s", 451 remote_major, remote_minor, remote_version); 452 453 ssh->compat = compat_datafellows(remote_version); 454 455 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 456 logit("probed from %s port %d with %s. Don't panic.", 457 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 458 client_version_string); 459 cleanup_exit(255); 460 } 461 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 462 logit("scanned from %s port %d with %s. Don't panic.", 463 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 464 client_version_string); 465 cleanup_exit(255); 466 } 467 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 468 logit("Client version \"%.100s\" uses unsafe RSA signature " 469 "scheme; disabling use of RSA keys", remote_version); 470 } 471 472 chop(server_version_string); 473 debug("Local version string %.200s", server_version_string); 474 475 if (remote_major != 2 && 476 !(remote_major == 1 && remote_minor == 99)) { 477 s = "Protocol major versions differ.\n"; 478 (void) atomicio(vwrite, sock_out, s, strlen(s)); 479 close(sock_in); 480 close(sock_out); 481 logit("Protocol major versions differ for %s port %d: " 482 "%.200s vs. %.200s", 483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 484 server_version_string, client_version_string); 485 cleanup_exit(255); 486 } 487 } 488 489 /* Destroy the host and server keys. They will no longer be needed. */ 490 void 491 destroy_sensitive_data(void) 492 { 493 u_int i; 494 495 for (i = 0; i < options.num_host_key_files; i++) { 496 if (sensitive_data.host_keys[i]) { 497 key_free(sensitive_data.host_keys[i]); 498 sensitive_data.host_keys[i] = NULL; 499 } 500 if (sensitive_data.host_certificates[i]) { 501 key_free(sensitive_data.host_certificates[i]); 502 sensitive_data.host_certificates[i] = NULL; 503 } 504 } 505 } 506 507 /* Demote private to public keys for network child */ 508 void 509 demote_sensitive_data(void) 510 { 511 struct sshkey *tmp; 512 u_int i; 513 514 for (i = 0; i < options.num_host_key_files; i++) { 515 if (sensitive_data.host_keys[i]) { 516 tmp = key_demote(sensitive_data.host_keys[i]); 517 key_free(sensitive_data.host_keys[i]); 518 sensitive_data.host_keys[i] = tmp; 519 } 520 /* Certs do not need demotion */ 521 } 522 } 523 524 static void 525 reseed_prngs(void) 526 { 527 u_int32_t rnd[256]; 528 529 #ifdef WITH_OPENSSL 530 RAND_poll(); 531 #endif 532 arc4random_stir(); /* noop on recent arc4random() implementations */ 533 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 534 535 #ifdef WITH_OPENSSL 536 RAND_seed(rnd, sizeof(rnd)); 537 /* give libcrypto a chance to notice the PID change */ 538 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 539 fatal("%s: RAND_bytes failed", __func__); 540 #endif 541 542 explicit_bzero(rnd, sizeof(rnd)); 543 } 544 545 static void 546 privsep_preauth_child(void) 547 { 548 gid_t gidset[1]; 549 550 /* Enable challenge-response authentication for privilege separation */ 551 privsep_challenge_enable(); 552 553 #ifdef GSSAPI 554 /* Cache supported mechanism OIDs for later use */ 555 if (options.gss_authentication) 556 ssh_gssapi_prepare_supported_oids(); 557 #endif 558 559 reseed_prngs(); 560 561 /* Demote the private keys to public keys. */ 562 demote_sensitive_data(); 563 564 /* Demote the child */ 565 if (privsep_chroot) { 566 /* Change our root directory */ 567 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 568 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 569 strerror(errno)); 570 if (chdir("/") == -1) 571 fatal("chdir(\"/\"): %s", strerror(errno)); 572 573 /* Drop our privileges */ 574 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 575 (u_int)privsep_pw->pw_gid); 576 gidset[0] = privsep_pw->pw_gid; 577 if (setgroups(1, gidset) < 0) 578 fatal("setgroups: %.100s", strerror(errno)); 579 permanently_set_uid(privsep_pw); 580 } 581 } 582 583 static int 584 privsep_preauth(Authctxt *authctxt) 585 { 586 int status, r; 587 pid_t pid; 588 struct ssh_sandbox *box = NULL; 589 590 /* Set up unprivileged child process to deal with network data */ 591 pmonitor = monitor_init(); 592 /* Store a pointer to the kex for later rekeying */ 593 pmonitor->m_pkex = &active_state->kex; 594 595 if (use_privsep == PRIVSEP_ON) 596 box = ssh_sandbox_init(pmonitor); 597 pid = fork(); 598 if (pid == -1) { 599 fatal("fork of unprivileged child failed"); 600 } else if (pid != 0) { 601 debug2("Network child is on pid %ld", (long)pid); 602 603 pmonitor->m_pid = pid; 604 if (have_agent) { 605 r = ssh_get_authentication_socket(&auth_sock); 606 if (r != 0) { 607 error("Could not get agent socket: %s", 608 ssh_err(r)); 609 have_agent = 0; 610 } 611 } 612 if (box != NULL) 613 ssh_sandbox_parent_preauth(box, pid); 614 monitor_child_preauth(authctxt, pmonitor); 615 616 /* Wait for the child's exit status */ 617 while (waitpid(pid, &status, 0) < 0) { 618 if (errno == EINTR) 619 continue; 620 pmonitor->m_pid = -1; 621 fatal("%s: waitpid: %s", __func__, strerror(errno)); 622 } 623 privsep_is_preauth = 0; 624 pmonitor->m_pid = -1; 625 if (WIFEXITED(status)) { 626 if (WEXITSTATUS(status) != 0) 627 fatal("%s: preauth child exited with status %d", 628 __func__, WEXITSTATUS(status)); 629 } else if (WIFSIGNALED(status)) 630 fatal("%s: preauth child terminated by signal %d", 631 __func__, WTERMSIG(status)); 632 if (box != NULL) 633 ssh_sandbox_parent_finish(box); 634 return 1; 635 } else { 636 /* child */ 637 close(pmonitor->m_sendfd); 638 close(pmonitor->m_log_recvfd); 639 640 /* Arrange for logging to be sent to the monitor */ 641 set_log_handler(mm_log_handler, pmonitor); 642 643 privsep_preauth_child(); 644 setproctitle("%s", "[net]"); 645 if (box != NULL) 646 ssh_sandbox_child(box); 647 648 return 0; 649 } 650 } 651 652 static void 653 privsep_postauth(Authctxt *authctxt) 654 { 655 #ifdef DISABLE_FD_PASSING 656 if (1) { 657 #else 658 if (authctxt->pw->pw_uid == 0) { 659 #endif 660 /* File descriptor passing is broken or root login */ 661 use_privsep = 0; 662 goto skip; 663 } 664 665 /* New socket pair */ 666 monitor_reinit(pmonitor); 667 668 pmonitor->m_pid = fork(); 669 if (pmonitor->m_pid == -1) 670 fatal("fork of unprivileged child failed"); 671 else if (pmonitor->m_pid != 0) { 672 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 673 buffer_clear(&loginmsg); 674 monitor_clear_keystate(pmonitor); 675 monitor_child_postauth(pmonitor); 676 677 /* NEVERREACHED */ 678 exit(0); 679 } 680 681 /* child */ 682 683 close(pmonitor->m_sendfd); 684 pmonitor->m_sendfd = -1; 685 686 /* Demote the private keys to public keys. */ 687 demote_sensitive_data(); 688 689 reseed_prngs(); 690 691 /* Drop privileges */ 692 do_setusercontext(authctxt->pw); 693 694 skip: 695 /* It is safe now to apply the key state */ 696 monitor_apply_keystate(pmonitor); 697 698 /* 699 * Tell the packet layer that authentication was successful, since 700 * this information is not part of the key state. 701 */ 702 packet_set_authenticated(); 703 } 704 705 static char * 706 list_hostkey_types(void) 707 { 708 Buffer b; 709 const char *p; 710 char *ret; 711 u_int i; 712 struct sshkey *key; 713 714 buffer_init(&b); 715 for (i = 0; i < options.num_host_key_files; i++) { 716 key = sensitive_data.host_keys[i]; 717 if (key == NULL) 718 key = sensitive_data.host_pubkeys[i]; 719 if (key == NULL) 720 continue; 721 /* Check that the key is accepted in HostkeyAlgorithms */ 722 if (match_pattern_list(sshkey_ssh_name(key), 723 options.hostkeyalgorithms, 0) != 1) { 724 debug3("%s: %s key not permitted by HostkeyAlgorithms", 725 __func__, sshkey_ssh_name(key)); 726 continue; 727 } 728 switch (key->type) { 729 case KEY_RSA: 730 case KEY_DSA: 731 case KEY_ECDSA: 732 case KEY_ED25519: 733 case KEY_XMSS: 734 if (buffer_len(&b) > 0) 735 buffer_append(&b, ",", 1); 736 p = key_ssh_name(key); 737 buffer_append(&b, p, strlen(p)); 738 739 /* for RSA we also support SHA2 signatures */ 740 if (key->type == KEY_RSA) { 741 p = ",rsa-sha2-512,rsa-sha2-256"; 742 buffer_append(&b, p, strlen(p)); 743 } 744 break; 745 } 746 /* If the private key has a cert peer, then list that too */ 747 key = sensitive_data.host_certificates[i]; 748 if (key == NULL) 749 continue; 750 switch (key->type) { 751 case KEY_RSA_CERT: 752 case KEY_DSA_CERT: 753 case KEY_ECDSA_CERT: 754 case KEY_ED25519_CERT: 755 case KEY_XMSS_CERT: 756 if (buffer_len(&b) > 0) 757 buffer_append(&b, ",", 1); 758 p = key_ssh_name(key); 759 buffer_append(&b, p, strlen(p)); 760 break; 761 } 762 } 763 if ((ret = sshbuf_dup_string(&b)) == NULL) 764 fatal("%s: sshbuf_dup_string failed", __func__); 765 buffer_free(&b); 766 debug("list_hostkey_types: %s", ret); 767 return ret; 768 } 769 770 static struct sshkey * 771 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 772 { 773 u_int i; 774 struct sshkey *key; 775 776 for (i = 0; i < options.num_host_key_files; i++) { 777 switch (type) { 778 case KEY_RSA_CERT: 779 case KEY_DSA_CERT: 780 case KEY_ECDSA_CERT: 781 case KEY_ED25519_CERT: 782 case KEY_XMSS_CERT: 783 key = sensitive_data.host_certificates[i]; 784 break; 785 default: 786 key = sensitive_data.host_keys[i]; 787 if (key == NULL && !need_private) 788 key = sensitive_data.host_pubkeys[i]; 789 break; 790 } 791 if (key != NULL && key->type == type && 792 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 793 return need_private ? 794 sensitive_data.host_keys[i] : key; 795 } 796 return NULL; 797 } 798 799 struct sshkey * 800 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 801 { 802 return get_hostkey_by_type(type, nid, 0, ssh); 803 } 804 805 struct sshkey * 806 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 807 { 808 return get_hostkey_by_type(type, nid, 1, ssh); 809 } 810 811 struct sshkey * 812 get_hostkey_by_index(int ind) 813 { 814 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 815 return (NULL); 816 return (sensitive_data.host_keys[ind]); 817 } 818 819 struct sshkey * 820 get_hostkey_public_by_index(int ind, struct ssh *ssh) 821 { 822 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 823 return (NULL); 824 return (sensitive_data.host_pubkeys[ind]); 825 } 826 827 int 828 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 829 { 830 u_int i; 831 832 for (i = 0; i < options.num_host_key_files; i++) { 833 if (key_is_cert(key)) { 834 if (key == sensitive_data.host_certificates[i] || 835 (compare && sensitive_data.host_certificates[i] && 836 sshkey_equal(key, 837 sensitive_data.host_certificates[i]))) 838 return (i); 839 } else { 840 if (key == sensitive_data.host_keys[i] || 841 (compare && sensitive_data.host_keys[i] && 842 sshkey_equal(key, sensitive_data.host_keys[i]))) 843 return (i); 844 if (key == sensitive_data.host_pubkeys[i] || 845 (compare && sensitive_data.host_pubkeys[i] && 846 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 847 return (i); 848 } 849 } 850 return (-1); 851 } 852 853 /* Inform the client of all hostkeys */ 854 static void 855 notify_hostkeys(struct ssh *ssh) 856 { 857 struct sshbuf *buf; 858 struct sshkey *key; 859 u_int i, nkeys; 860 int r; 861 char *fp; 862 863 /* Some clients cannot cope with the hostkeys message, skip those. */ 864 if (datafellows & SSH_BUG_HOSTKEYS) 865 return; 866 867 if ((buf = sshbuf_new()) == NULL) 868 fatal("%s: sshbuf_new", __func__); 869 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 870 key = get_hostkey_public_by_index(i, ssh); 871 if (key == NULL || key->type == KEY_UNSPEC || 872 sshkey_is_cert(key)) 873 continue; 874 fp = sshkey_fingerprint(key, options.fingerprint_hash, 875 SSH_FP_DEFAULT); 876 debug3("%s: key %d: %s %s", __func__, i, 877 sshkey_ssh_name(key), fp); 878 free(fp); 879 if (nkeys == 0) { 880 packet_start(SSH2_MSG_GLOBAL_REQUEST); 881 packet_put_cstring("hostkeys-00@openssh.com"); 882 packet_put_char(0); /* want-reply */ 883 } 884 sshbuf_reset(buf); 885 if ((r = sshkey_putb(key, buf)) != 0) 886 fatal("%s: couldn't put hostkey %d: %s", 887 __func__, i, ssh_err(r)); 888 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 889 nkeys++; 890 } 891 debug3("%s: sent %u hostkeys", __func__, nkeys); 892 if (nkeys == 0) 893 fatal("%s: no hostkeys", __func__); 894 packet_send(); 895 sshbuf_free(buf); 896 } 897 898 /* 899 * returns 1 if connection should be dropped, 0 otherwise. 900 * dropping starts at connection #max_startups_begin with a probability 901 * of (max_startups_rate/100). the probability increases linearly until 902 * all connections are dropped for startups > max_startups 903 */ 904 static int 905 drop_connection(int startups) 906 { 907 int p, r; 908 909 if (startups < options.max_startups_begin) 910 return 0; 911 if (startups >= options.max_startups) 912 return 1; 913 if (options.max_startups_rate == 100) 914 return 1; 915 916 p = 100 - options.max_startups_rate; 917 p *= startups - options.max_startups_begin; 918 p /= options.max_startups - options.max_startups_begin; 919 p += options.max_startups_rate; 920 r = arc4random_uniform(100); 921 922 debug("drop_connection: p %d, r %d", p, r); 923 return (r < p) ? 1 : 0; 924 } 925 926 static void 927 usage(void) 928 { 929 if (options.version_addendum && *options.version_addendum != '\0') 930 fprintf(stderr, "%s %s, %s\n", 931 SSH_RELEASE, 932 options.version_addendum, OPENSSL_VERSION); 933 else 934 fprintf(stderr, "%s, %s\n", 935 SSH_RELEASE, OPENSSL_VERSION); 936 fprintf(stderr, 937 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 938 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 939 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 940 ); 941 exit(1); 942 } 943 944 static void 945 send_rexec_state(int fd, struct sshbuf *conf) 946 { 947 struct sshbuf *m; 948 int r; 949 950 debug3("%s: entering fd = %d config len %zu", __func__, fd, 951 sshbuf_len(conf)); 952 953 /* 954 * Protocol from reexec master to child: 955 * string configuration 956 * string rngseed (only if OpenSSL is not self-seeded) 957 */ 958 if ((m = sshbuf_new()) == NULL) 959 fatal("%s: sshbuf_new failed", __func__); 960 if ((r = sshbuf_put_stringb(m, conf)) != 0) 961 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 962 963 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 964 rexec_send_rng_seed(m); 965 #endif 966 967 if (ssh_msg_send(fd, 0, m) == -1) 968 fatal("%s: ssh_msg_send failed", __func__); 969 970 sshbuf_free(m); 971 972 debug3("%s: done", __func__); 973 } 974 975 static void 976 recv_rexec_state(int fd, Buffer *conf) 977 { 978 Buffer m; 979 char *cp; 980 u_int len; 981 982 debug3("%s: entering fd = %d", __func__, fd); 983 984 buffer_init(&m); 985 986 if (ssh_msg_recv(fd, &m) == -1) 987 fatal("%s: ssh_msg_recv failed", __func__); 988 if (buffer_get_char(&m) != 0) 989 fatal("%s: rexec version mismatch", __func__); 990 991 cp = buffer_get_string(&m, &len); 992 if (conf != NULL) 993 buffer_append(conf, cp, len); 994 free(cp); 995 996 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 997 rexec_recv_rng_seed(&m); 998 #endif 999 1000 buffer_free(&m); 1001 1002 debug3("%s: done", __func__); 1003 } 1004 1005 /* Accept a connection from inetd */ 1006 static void 1007 server_accept_inetd(int *sock_in, int *sock_out) 1008 { 1009 int fd; 1010 1011 startup_pipe = -1; 1012 if (rexeced_flag) { 1013 close(REEXEC_CONFIG_PASS_FD); 1014 *sock_in = *sock_out = dup(STDIN_FILENO); 1015 if (!debug_flag) { 1016 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1017 close(REEXEC_STARTUP_PIPE_FD); 1018 } 1019 } else { 1020 *sock_in = dup(STDIN_FILENO); 1021 *sock_out = dup(STDOUT_FILENO); 1022 } 1023 /* 1024 * We intentionally do not close the descriptors 0, 1, and 2 1025 * as our code for setting the descriptors won't work if 1026 * ttyfd happens to be one of those. 1027 */ 1028 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1029 dup2(fd, STDIN_FILENO); 1030 dup2(fd, STDOUT_FILENO); 1031 if (!log_stderr) 1032 dup2(fd, STDERR_FILENO); 1033 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1034 close(fd); 1035 } 1036 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1037 } 1038 1039 /* 1040 * Listen for TCP connections 1041 */ 1042 static void 1043 listen_on_addrs(struct listenaddr *la) 1044 { 1045 int ret, listen_sock; 1046 struct addrinfo *ai; 1047 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1048 int socksize; 1049 socklen_t len; 1050 1051 for (ai = la->addrs; ai; ai = ai->ai_next) { 1052 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1053 continue; 1054 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1055 fatal("Too many listen sockets. " 1056 "Enlarge MAX_LISTEN_SOCKS"); 1057 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1058 ntop, sizeof(ntop), strport, sizeof(strport), 1059 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1060 error("getnameinfo failed: %.100s", 1061 ssh_gai_strerror(ret)); 1062 continue; 1063 } 1064 /* Create socket for listening. */ 1065 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1066 ai->ai_protocol); 1067 if (listen_sock < 0) { 1068 /* kernel may not support ipv6 */ 1069 verbose("socket: %.100s", strerror(errno)); 1070 continue; 1071 } 1072 if (set_nonblock(listen_sock) == -1) { 1073 close(listen_sock); 1074 continue; 1075 } 1076 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1077 verbose("socket: CLOEXEC: %s", strerror(errno)); 1078 close(listen_sock); 1079 continue; 1080 } 1081 /* Socket options */ 1082 set_reuseaddr(listen_sock); 1083 if (la->rdomain != NULL && 1084 set_rdomain(listen_sock, la->rdomain) == -1) { 1085 close(listen_sock); 1086 continue; 1087 } 1088 1089 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1090 if (ai->ai_family == AF_INET6) 1091 sock_set_v6only(listen_sock); 1092 1093 debug("Bind to port %s on %s.", strport, ntop); 1094 1095 len = sizeof(socksize); 1096 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1097 debug("Server TCP RWIN socket size: %d", socksize); 1098 1099 /* Bind the socket to the desired port. */ 1100 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1101 error("Bind to port %s on %s failed: %.200s.", 1102 strport, ntop, strerror(errno)); 1103 close(listen_sock); 1104 continue; 1105 } 1106 listen_socks[num_listen_socks] = listen_sock; 1107 num_listen_socks++; 1108 1109 /* Start listening on the port. */ 1110 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1111 fatal("listen on [%s]:%s: %.100s", 1112 ntop, strport, strerror(errno)); 1113 logit("Server listening on %s port %s%s%s.", 1114 ntop, strport, 1115 la->rdomain == NULL ? "" : " rdomain ", 1116 la->rdomain == NULL ? "" : la->rdomain); 1117 } 1118 } 1119 1120 static void 1121 server_listen(void) 1122 { 1123 u_int i; 1124 1125 for (i = 0; i < options.num_listen_addrs; i++) { 1126 listen_on_addrs(&options.listen_addrs[i]); 1127 freeaddrinfo(options.listen_addrs[i].addrs); 1128 free(options.listen_addrs[i].rdomain); 1129 memset(&options.listen_addrs[i], 0, 1130 sizeof(options.listen_addrs[i])); 1131 } 1132 free(options.listen_addrs); 1133 options.listen_addrs = NULL; 1134 options.num_listen_addrs = 0; 1135 1136 if (!num_listen_socks) 1137 fatal("Cannot bind any address."); 1138 } 1139 1140 /* 1141 * The main TCP accept loop. Note that, for the non-debug case, returns 1142 * from this function are in a forked subprocess. 1143 */ 1144 static void 1145 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1146 { 1147 fd_set *fdset; 1148 int i, j, ret, maxfd; 1149 int startups = 0; 1150 int startup_p[2] = { -1 , -1 }; 1151 struct sockaddr_storage from; 1152 socklen_t fromlen; 1153 pid_t pid; 1154 u_char rnd[256]; 1155 1156 /* setup fd set for accept */ 1157 fdset = NULL; 1158 maxfd = 0; 1159 for (i = 0; i < num_listen_socks; i++) 1160 if (listen_socks[i] > maxfd) 1161 maxfd = listen_socks[i]; 1162 /* pipes connected to unauthenticated childs */ 1163 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1164 for (i = 0; i < options.max_startups; i++) 1165 startup_pipes[i] = -1; 1166 1167 /* 1168 * Stay listening for connections until the system crashes or 1169 * the daemon is killed with a signal. 1170 */ 1171 for (;;) { 1172 if (received_sighup) 1173 sighup_restart(); 1174 free(fdset); 1175 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1176 sizeof(fd_mask)); 1177 1178 for (i = 0; i < num_listen_socks; i++) 1179 FD_SET(listen_socks[i], fdset); 1180 for (i = 0; i < options.max_startups; i++) 1181 if (startup_pipes[i] != -1) 1182 FD_SET(startup_pipes[i], fdset); 1183 1184 /* Wait in select until there is a connection. */ 1185 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1186 if (ret < 0 && errno != EINTR) 1187 error("select: %.100s", strerror(errno)); 1188 if (received_sigterm) { 1189 logit("Received signal %d; terminating.", 1190 (int) received_sigterm); 1191 close_listen_socks(); 1192 if (options.pid_file != NULL) 1193 unlink(options.pid_file); 1194 exit(received_sigterm == SIGTERM ? 0 : 255); 1195 } 1196 if (ret < 0) 1197 continue; 1198 1199 for (i = 0; i < options.max_startups; i++) 1200 if (startup_pipes[i] != -1 && 1201 FD_ISSET(startup_pipes[i], fdset)) { 1202 /* 1203 * the read end of the pipe is ready 1204 * if the child has closed the pipe 1205 * after successful authentication 1206 * or if the child has died 1207 */ 1208 close(startup_pipes[i]); 1209 startup_pipes[i] = -1; 1210 startups--; 1211 } 1212 for (i = 0; i < num_listen_socks; i++) { 1213 if (!FD_ISSET(listen_socks[i], fdset)) 1214 continue; 1215 fromlen = sizeof(from); 1216 *newsock = accept(listen_socks[i], 1217 (struct sockaddr *)&from, &fromlen); 1218 if (*newsock < 0) { 1219 if (errno != EINTR && errno != EWOULDBLOCK && 1220 errno != ECONNABORTED && errno != EAGAIN) 1221 error("accept: %.100s", 1222 strerror(errno)); 1223 if (errno == EMFILE || errno == ENFILE) 1224 usleep(100 * 1000); 1225 continue; 1226 } 1227 if (unset_nonblock(*newsock) == -1) { 1228 close(*newsock); 1229 continue; 1230 } 1231 if (drop_connection(startups) == 1) { 1232 char *laddr = get_local_ipaddr(*newsock); 1233 char *raddr = get_peer_ipaddr(*newsock); 1234 1235 verbose("drop connection #%d from [%s]:%d " 1236 "on [%s]:%d past MaxStartups", startups, 1237 raddr, get_peer_port(*newsock), 1238 laddr, get_local_port(*newsock)); 1239 free(laddr); 1240 free(raddr); 1241 close(*newsock); 1242 continue; 1243 } 1244 if (pipe(startup_p) == -1) { 1245 close(*newsock); 1246 continue; 1247 } 1248 1249 if (rexec_flag && socketpair(AF_UNIX, 1250 SOCK_STREAM, 0, config_s) == -1) { 1251 error("reexec socketpair: %s", 1252 strerror(errno)); 1253 close(*newsock); 1254 close(startup_p[0]); 1255 close(startup_p[1]); 1256 continue; 1257 } 1258 1259 for (j = 0; j < options.max_startups; j++) 1260 if (startup_pipes[j] == -1) { 1261 startup_pipes[j] = startup_p[0]; 1262 if (maxfd < startup_p[0]) 1263 maxfd = startup_p[0]; 1264 startups++; 1265 break; 1266 } 1267 1268 /* 1269 * Got connection. Fork a child to handle it, unless 1270 * we are in debugging mode. 1271 */ 1272 if (debug_flag) { 1273 /* 1274 * In debugging mode. Close the listening 1275 * socket, and start processing the 1276 * connection without forking. 1277 */ 1278 debug("Server will not fork when running in debugging mode."); 1279 close_listen_socks(); 1280 *sock_in = *newsock; 1281 *sock_out = *newsock; 1282 close(startup_p[0]); 1283 close(startup_p[1]); 1284 startup_pipe = -1; 1285 pid = getpid(); 1286 if (rexec_flag) { 1287 send_rexec_state(config_s[0], 1288 &cfg); 1289 close(config_s[0]); 1290 } 1291 break; 1292 } 1293 1294 /* 1295 * Normal production daemon. Fork, and have 1296 * the child process the connection. The 1297 * parent continues listening. 1298 */ 1299 platform_pre_fork(); 1300 if ((pid = fork()) == 0) { 1301 /* 1302 * Child. Close the listening and 1303 * max_startup sockets. Start using 1304 * the accepted socket. Reinitialize 1305 * logging (since our pid has changed). 1306 * We break out of the loop to handle 1307 * the connection. 1308 */ 1309 platform_post_fork_child(); 1310 startup_pipe = startup_p[1]; 1311 close_startup_pipes(); 1312 close_listen_socks(); 1313 *sock_in = *newsock; 1314 *sock_out = *newsock; 1315 log_init(__progname, 1316 options.log_level, 1317 options.log_facility, 1318 log_stderr); 1319 if (rexec_flag) 1320 close(config_s[0]); 1321 break; 1322 } 1323 1324 /* Parent. Stay in the loop. */ 1325 platform_post_fork_parent(pid); 1326 if (pid < 0) 1327 error("fork: %.100s", strerror(errno)); 1328 else 1329 debug("Forked child %ld.", (long)pid); 1330 1331 close(startup_p[1]); 1332 1333 if (rexec_flag) { 1334 send_rexec_state(config_s[0], &cfg); 1335 close(config_s[0]); 1336 close(config_s[1]); 1337 } 1338 close(*newsock); 1339 1340 /* 1341 * Ensure that our random state differs 1342 * from that of the child 1343 */ 1344 arc4random_stir(); 1345 arc4random_buf(rnd, sizeof(rnd)); 1346 #ifdef WITH_OPENSSL 1347 RAND_seed(rnd, sizeof(rnd)); 1348 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1349 fatal("%s: RAND_bytes failed", __func__); 1350 #endif 1351 explicit_bzero(rnd, sizeof(rnd)); 1352 } 1353 1354 /* child process check (or debug mode) */ 1355 if (num_listen_socks < 0) 1356 break; 1357 } 1358 } 1359 1360 /* 1361 * If IP options are supported, make sure there are none (log and 1362 * return an error if any are found). Basically we are worried about 1363 * source routing; it can be used to pretend you are somebody 1364 * (ip-address) you are not. That itself may be "almost acceptable" 1365 * under certain circumstances, but rhosts autentication is useless 1366 * if source routing is accepted. Notice also that if we just dropped 1367 * source routing here, the other side could use IP spoofing to do 1368 * rest of the interaction and could still bypass security. So we 1369 * exit here if we detect any IP options. 1370 */ 1371 static void 1372 check_ip_options(struct ssh *ssh) 1373 { 1374 #ifdef IP_OPTIONS 1375 int sock_in = ssh_packet_get_connection_in(ssh); 1376 struct sockaddr_storage from; 1377 u_char opts[200]; 1378 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1379 char text[sizeof(opts) * 3 + 1]; 1380 1381 memset(&from, 0, sizeof(from)); 1382 if (getpeername(sock_in, (struct sockaddr *)&from, 1383 &fromlen) < 0) 1384 return; 1385 if (from.ss_family != AF_INET) 1386 return; 1387 /* XXX IPv6 options? */ 1388 1389 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1390 &option_size) >= 0 && option_size != 0) { 1391 text[0] = '\0'; 1392 for (i = 0; i < option_size; i++) 1393 snprintf(text + i*3, sizeof(text) - i*3, 1394 " %2.2x", opts[i]); 1395 fatal("Connection from %.100s port %d with IP opts: %.800s", 1396 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1397 } 1398 return; 1399 #endif /* IP_OPTIONS */ 1400 } 1401 1402 /* Set the routing domain for this process */ 1403 static void 1404 set_process_rdomain(struct ssh *ssh, const char *name) 1405 { 1406 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 1407 if (name == NULL) 1408 return; /* default */ 1409 1410 if (strcmp(name, "%D") == 0) { 1411 /* "expands" to routing domain of connection */ 1412 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1413 return; 1414 } 1415 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 1416 return sys_set_process_rdomain(name); 1417 #elif defined(__OpenBSD__) 1418 int rtable, ortable = getrtable(); 1419 const char *errstr; 1420 1421 if (name == NULL) 1422 return; /* default */ 1423 1424 if (strcmp(name, "%D") == 0) { 1425 /* "expands" to routing domain of connection */ 1426 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1427 return; 1428 } 1429 1430 rtable = (int)strtonum(name, 0, 255, &errstr); 1431 if (errstr != NULL) /* Shouldn't happen */ 1432 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1433 if (rtable != ortable && setrtable(rtable) != 0) 1434 fatal("Unable to set routing domain %d: %s", 1435 rtable, strerror(errno)); 1436 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1437 #else /* defined(__OpenBSD__) */ 1438 fatal("Unable to set routing domain: not supported in this platform"); 1439 #endif 1440 } 1441 1442 /* 1443 * Main program for the daemon. 1444 */ 1445 int 1446 main(int ac, char **av) 1447 { 1448 struct ssh *ssh = NULL; 1449 extern char *optarg; 1450 extern int optind; 1451 int r, opt, on = 1, already_daemon, remote_port; 1452 int sock_in = -1, sock_out = -1, newsock = -1; 1453 const char *remote_ip, *rdomain; 1454 char *fp, *line, *laddr, *logfile = NULL; 1455 int config_s[2] = { -1 , -1 }; 1456 u_int i, j; 1457 u_int64_t ibytes, obytes; 1458 mode_t new_umask; 1459 struct sshkey *key; 1460 struct sshkey *pubkey; 1461 int keytype; 1462 Authctxt *authctxt; 1463 struct connection_info *connection_info = NULL; 1464 1465 ssh_malloc_init(); /* must be called before any mallocs */ 1466 1467 #ifdef HAVE_SECUREWARE 1468 (void)set_auth_parameters(ac, av); 1469 #endif 1470 __progname = ssh_get_progname(av[0]); 1471 1472 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1473 saved_argc = ac; 1474 rexec_argc = ac; 1475 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1476 for (i = 0; (int)i < ac; i++) 1477 saved_argv[i] = xstrdup(av[i]); 1478 saved_argv[i] = NULL; 1479 1480 #ifndef HAVE_SETPROCTITLE 1481 /* Prepare for later setproctitle emulation */ 1482 compat_init_setproctitle(ac, av); 1483 av = saved_argv; 1484 #endif 1485 1486 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1487 debug("setgroups(): %.200s", strerror(errno)); 1488 1489 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1490 sanitise_stdfd(); 1491 1492 /* Initialize configuration options to their default values. */ 1493 initialize_server_options(&options); 1494 1495 /* Parse command-line arguments. */ 1496 while ((opt = getopt(ac, av, 1497 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1498 switch (opt) { 1499 case '4': 1500 options.address_family = AF_INET; 1501 break; 1502 case '6': 1503 options.address_family = AF_INET6; 1504 break; 1505 case 'f': 1506 config_file_name = optarg; 1507 break; 1508 case 'c': 1509 servconf_add_hostcert("[command-line]", 0, 1510 &options, optarg); 1511 break; 1512 case 'd': 1513 if (debug_flag == 0) { 1514 debug_flag = 1; 1515 options.log_level = SYSLOG_LEVEL_DEBUG1; 1516 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1517 options.log_level++; 1518 break; 1519 case 'D': 1520 no_daemon_flag = 1; 1521 break; 1522 case 'E': 1523 logfile = optarg; 1524 /* FALLTHROUGH */ 1525 case 'e': 1526 log_stderr = 1; 1527 break; 1528 case 'i': 1529 inetd_flag = 1; 1530 break; 1531 case 'r': 1532 rexec_flag = 0; 1533 break; 1534 case 'R': 1535 rexeced_flag = 1; 1536 inetd_flag = 1; 1537 break; 1538 case 'Q': 1539 /* ignored */ 1540 break; 1541 case 'q': 1542 options.log_level = SYSLOG_LEVEL_QUIET; 1543 break; 1544 case 'b': 1545 /* protocol 1, ignored */ 1546 break; 1547 case 'p': 1548 options.ports_from_cmdline = 1; 1549 if (options.num_ports >= MAX_PORTS) { 1550 fprintf(stderr, "too many ports.\n"); 1551 exit(1); 1552 } 1553 options.ports[options.num_ports++] = a2port(optarg); 1554 if (options.ports[options.num_ports-1] <= 0) { 1555 fprintf(stderr, "Bad port number.\n"); 1556 exit(1); 1557 } 1558 break; 1559 case 'g': 1560 if ((options.login_grace_time = convtime(optarg)) == -1) { 1561 fprintf(stderr, "Invalid login grace time.\n"); 1562 exit(1); 1563 } 1564 break; 1565 case 'k': 1566 /* protocol 1, ignored */ 1567 break; 1568 case 'h': 1569 servconf_add_hostkey("[command-line]", 0, 1570 &options, optarg); 1571 break; 1572 case 't': 1573 test_flag = 1; 1574 break; 1575 case 'T': 1576 test_flag = 2; 1577 break; 1578 case 'C': 1579 connection_info = get_connection_info(0, 0); 1580 if (parse_server_match_testspec(connection_info, 1581 optarg) == -1) 1582 exit(1); 1583 break; 1584 case 'u': 1585 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1586 if (utmp_len > HOST_NAME_MAX+1) { 1587 fprintf(stderr, "Invalid utmp length.\n"); 1588 exit(1); 1589 } 1590 break; 1591 case 'o': 1592 line = xstrdup(optarg); 1593 if (process_server_config_line(&options, line, 1594 "command-line", 0, NULL, NULL) != 0) 1595 exit(1); 1596 free(line); 1597 break; 1598 case '?': 1599 default: 1600 usage(); 1601 break; 1602 } 1603 } 1604 if (rexeced_flag || inetd_flag) 1605 rexec_flag = 0; 1606 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1607 fatal("sshd re-exec requires execution with an absolute path"); 1608 if (rexeced_flag) 1609 closefrom(REEXEC_MIN_FREE_FD); 1610 else 1611 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1612 1613 #ifdef WITH_OPENSSL 1614 OpenSSL_add_all_algorithms(); 1615 #endif 1616 1617 /* If requested, redirect the logs to the specified logfile. */ 1618 if (logfile != NULL) 1619 log_redirect_stderr_to(logfile); 1620 /* 1621 * Force logging to stderr until we have loaded the private host 1622 * key (unless started from inetd) 1623 */ 1624 log_init(__progname, 1625 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1626 SYSLOG_LEVEL_INFO : options.log_level, 1627 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1628 SYSLOG_FACILITY_AUTH : options.log_facility, 1629 log_stderr || !inetd_flag); 1630 1631 /* 1632 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1633 * root's environment 1634 */ 1635 if (getenv("KRB5CCNAME") != NULL) 1636 (void) unsetenv("KRB5CCNAME"); 1637 1638 sensitive_data.have_ssh2_key = 0; 1639 1640 /* 1641 * If we're not doing an extended test do not silently ignore connection 1642 * test params. 1643 */ 1644 if (test_flag < 2 && connection_info != NULL) 1645 fatal("Config test connection parameter (-C) provided without " 1646 "test mode (-T)"); 1647 1648 /* Fetch our configuration */ 1649 buffer_init(&cfg); 1650 if (rexeced_flag) 1651 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1652 else if (strcasecmp(config_file_name, "none") != 0) 1653 load_server_config(config_file_name, &cfg); 1654 1655 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1656 &cfg, NULL); 1657 1658 seed_rng(); 1659 1660 /* Fill in default values for those options not explicitly set. */ 1661 fill_default_server_options(&options); 1662 1663 /* challenge-response is implemented via keyboard interactive */ 1664 if (options.challenge_response_authentication) 1665 options.kbd_interactive_authentication = 1; 1666 1667 /* Check that options are sensible */ 1668 if (options.authorized_keys_command_user == NULL && 1669 (options.authorized_keys_command != NULL && 1670 strcasecmp(options.authorized_keys_command, "none") != 0)) 1671 fatal("AuthorizedKeysCommand set without " 1672 "AuthorizedKeysCommandUser"); 1673 if (options.authorized_principals_command_user == NULL && 1674 (options.authorized_principals_command != NULL && 1675 strcasecmp(options.authorized_principals_command, "none") != 0)) 1676 fatal("AuthorizedPrincipalsCommand set without " 1677 "AuthorizedPrincipalsCommandUser"); 1678 1679 /* 1680 * Check whether there is any path through configured auth methods. 1681 * Unfortunately it is not possible to verify this generally before 1682 * daemonisation in the presence of Match block, but this catches 1683 * and warns for trivial misconfigurations that could break login. 1684 */ 1685 if (options.num_auth_methods != 0) { 1686 for (i = 0; i < options.num_auth_methods; i++) { 1687 if (auth2_methods_valid(options.auth_methods[i], 1688 1) == 0) 1689 break; 1690 } 1691 if (i >= options.num_auth_methods) 1692 fatal("AuthenticationMethods cannot be satisfied by " 1693 "enabled authentication methods"); 1694 } 1695 1696 /* Check that there are no remaining arguments. */ 1697 if (optind < ac) { 1698 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1699 exit(1); 1700 } 1701 1702 debug("sshd version %s, %s", SSH_VERSION, 1703 #ifdef WITH_OPENSSL 1704 SSLeay_version(SSLEAY_VERSION) 1705 #else 1706 "without OpenSSL" 1707 #endif 1708 ); 1709 1710 /* Store privilege separation user for later use if required. */ 1711 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1712 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1713 if (privsep_chroot || options.kerberos_authentication) 1714 fatal("Privilege separation user %s does not exist", 1715 SSH_PRIVSEP_USER); 1716 } else { 1717 privsep_pw = pwcopy(privsep_pw); 1718 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1719 privsep_pw->pw_passwd = xstrdup("*"); 1720 } 1721 endpwent(); 1722 1723 /* load host keys */ 1724 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1725 sizeof(struct sshkey *)); 1726 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1727 sizeof(struct sshkey *)); 1728 1729 if (options.host_key_agent) { 1730 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1731 setenv(SSH_AUTHSOCKET_ENV_NAME, 1732 options.host_key_agent, 1); 1733 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1734 have_agent = 1; 1735 else 1736 error("Could not connect to agent \"%s\": %s", 1737 options.host_key_agent, ssh_err(r)); 1738 } 1739 1740 for (i = 0; i < options.num_host_key_files; i++) { 1741 if (options.host_key_files[i] == NULL) 1742 continue; 1743 key = key_load_private(options.host_key_files[i], "", NULL); 1744 pubkey = key_load_public(options.host_key_files[i], NULL); 1745 1746 if (pubkey == NULL && key != NULL) 1747 pubkey = key_demote(key); 1748 sensitive_data.host_keys[i] = key; 1749 sensitive_data.host_pubkeys[i] = pubkey; 1750 1751 if (key == NULL && pubkey != NULL && have_agent) { 1752 debug("will rely on agent for hostkey %s", 1753 options.host_key_files[i]); 1754 keytype = pubkey->type; 1755 } else if (key != NULL) { 1756 keytype = key->type; 1757 } else { 1758 error("Could not load host key: %s", 1759 options.host_key_files[i]); 1760 sensitive_data.host_keys[i] = NULL; 1761 sensitive_data.host_pubkeys[i] = NULL; 1762 continue; 1763 } 1764 1765 switch (keytype) { 1766 case KEY_RSA: 1767 case KEY_DSA: 1768 case KEY_ECDSA: 1769 case KEY_ED25519: 1770 case KEY_XMSS: 1771 if (have_agent || key != NULL) 1772 sensitive_data.have_ssh2_key = 1; 1773 break; 1774 } 1775 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1776 SSH_FP_DEFAULT)) == NULL) 1777 fatal("sshkey_fingerprint failed"); 1778 debug("%s host key #%d: %s %s", 1779 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1780 free(fp); 1781 } 1782 if (!sensitive_data.have_ssh2_key) { 1783 logit("sshd: no hostkeys available -- exiting."); 1784 exit(1); 1785 } 1786 1787 /* 1788 * Load certificates. They are stored in an array at identical 1789 * indices to the public keys that they relate to. 1790 */ 1791 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1792 sizeof(struct sshkey *)); 1793 for (i = 0; i < options.num_host_key_files; i++) 1794 sensitive_data.host_certificates[i] = NULL; 1795 1796 for (i = 0; i < options.num_host_cert_files; i++) { 1797 if (options.host_cert_files[i] == NULL) 1798 continue; 1799 key = key_load_public(options.host_cert_files[i], NULL); 1800 if (key == NULL) { 1801 error("Could not load host certificate: %s", 1802 options.host_cert_files[i]); 1803 continue; 1804 } 1805 if (!key_is_cert(key)) { 1806 error("Certificate file is not a certificate: %s", 1807 options.host_cert_files[i]); 1808 key_free(key); 1809 continue; 1810 } 1811 /* Find matching private key */ 1812 for (j = 0; j < options.num_host_key_files; j++) { 1813 if (key_equal_public(key, 1814 sensitive_data.host_keys[j])) { 1815 sensitive_data.host_certificates[j] = key; 1816 break; 1817 } 1818 } 1819 if (j >= options.num_host_key_files) { 1820 error("No matching private key for certificate: %s", 1821 options.host_cert_files[i]); 1822 key_free(key); 1823 continue; 1824 } 1825 sensitive_data.host_certificates[j] = key; 1826 debug("host certificate: #%u type %d %s", j, key->type, 1827 key_type(key)); 1828 } 1829 1830 if (privsep_chroot) { 1831 struct stat st; 1832 1833 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1834 (S_ISDIR(st.st_mode) == 0)) 1835 fatal("Missing privilege separation directory: %s", 1836 _PATH_PRIVSEP_CHROOT_DIR); 1837 1838 #ifdef HAVE_CYGWIN 1839 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1840 (st.st_uid != getuid () || 1841 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1842 #else 1843 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1844 #endif 1845 fatal("%s must be owned by root and not group or " 1846 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1847 } 1848 1849 if (test_flag > 1) { 1850 /* 1851 * If no connection info was provided by -C then use 1852 * use a blank one that will cause no predicate to match. 1853 */ 1854 if (connection_info == NULL) 1855 connection_info = get_connection_info(0, 0); 1856 parse_server_match_config(&options, connection_info); 1857 dump_config(&options); 1858 } 1859 1860 /* Configuration looks good, so exit if in test mode. */ 1861 if (test_flag) 1862 exit(0); 1863 1864 /* 1865 * Clear out any supplemental groups we may have inherited. This 1866 * prevents inadvertent creation of files with bad modes (in the 1867 * portable version at least, it's certainly possible for PAM 1868 * to create a file, and we can't control the code in every 1869 * module which might be used). 1870 */ 1871 if (setgroups(0, NULL) < 0) 1872 debug("setgroups() failed: %.200s", strerror(errno)); 1873 1874 if (rexec_flag) { 1875 if (rexec_argc < 0) 1876 fatal("rexec_argc %d < 0", rexec_argc); 1877 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1878 for (i = 0; i < (u_int)rexec_argc; i++) { 1879 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1880 rexec_argv[i] = saved_argv[i]; 1881 } 1882 rexec_argv[rexec_argc] = "-R"; 1883 rexec_argv[rexec_argc + 1] = NULL; 1884 } 1885 1886 /* Ensure that umask disallows at least group and world write */ 1887 new_umask = umask(0077) | 0022; 1888 (void) umask(new_umask); 1889 1890 /* Initialize the log (it is reinitialized below in case we forked). */ 1891 if (debug_flag && (!inetd_flag || rexeced_flag)) 1892 log_stderr = 1; 1893 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1894 1895 /* 1896 * If not in debugging mode, not started from inetd and not already 1897 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1898 * terminal, and fork. The original process exits. 1899 */ 1900 already_daemon = daemonized(); 1901 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1902 1903 if (daemon(0, 0) < 0) 1904 fatal("daemon() failed: %.200s", strerror(errno)); 1905 1906 disconnect_controlling_tty(); 1907 } 1908 /* Reinitialize the log (because of the fork above). */ 1909 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1910 1911 /* Avoid killing the process in high-pressure swapping environments. */ 1912 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1913 debug("madvise(): %.200s", strerror(errno)); 1914 1915 /* Chdir to the root directory so that the current disk can be 1916 unmounted if desired. */ 1917 if (chdir("/") == -1) 1918 error("chdir(\"/\"): %s", strerror(errno)); 1919 1920 /* ignore SIGPIPE */ 1921 signal(SIGPIPE, SIG_IGN); 1922 1923 /* Get a connection, either from inetd or a listening TCP socket */ 1924 if (inetd_flag) { 1925 server_accept_inetd(&sock_in, &sock_out); 1926 } else { 1927 platform_pre_listen(); 1928 server_listen(); 1929 1930 signal(SIGHUP, sighup_handler); 1931 signal(SIGCHLD, main_sigchld_handler); 1932 signal(SIGTERM, sigterm_handler); 1933 signal(SIGQUIT, sigterm_handler); 1934 1935 /* 1936 * Write out the pid file after the sigterm handler 1937 * is setup and the listen sockets are bound 1938 */ 1939 if (options.pid_file != NULL && !debug_flag) { 1940 FILE *f = fopen(options.pid_file, "w"); 1941 1942 if (f == NULL) { 1943 error("Couldn't create pid file \"%s\": %s", 1944 options.pid_file, strerror(errno)); 1945 } else { 1946 fprintf(f, "%ld\n", (long) getpid()); 1947 fclose(f); 1948 } 1949 } 1950 1951 /* Accept a connection and return in a forked child */ 1952 server_accept_loop(&sock_in, &sock_out, 1953 &newsock, config_s); 1954 } 1955 1956 /* This is the child processing a new connection. */ 1957 setproctitle("%s", "[accepted]"); 1958 1959 /* 1960 * Create a new session and process group since the 4.4BSD 1961 * setlogin() affects the entire process group. We don't 1962 * want the child to be able to affect the parent. 1963 */ 1964 #if !defined(SSHD_ACQUIRES_CTTY) 1965 /* 1966 * If setsid is called, on some platforms sshd will later acquire a 1967 * controlling terminal which will result in "could not set 1968 * controlling tty" errors. 1969 */ 1970 if (!debug_flag && !inetd_flag && setsid() < 0) 1971 error("setsid: %.100s", strerror(errno)); 1972 #endif 1973 1974 if (rexec_flag) { 1975 int fd; 1976 1977 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1978 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1979 dup2(newsock, STDIN_FILENO); 1980 dup2(STDIN_FILENO, STDOUT_FILENO); 1981 if (startup_pipe == -1) 1982 close(REEXEC_STARTUP_PIPE_FD); 1983 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1984 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1985 close(startup_pipe); 1986 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1987 } 1988 1989 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1990 close(config_s[1]); 1991 1992 execv(rexec_argv[0], rexec_argv); 1993 1994 /* Reexec has failed, fall back and continue */ 1995 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1996 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1997 log_init(__progname, options.log_level, 1998 options.log_facility, log_stderr); 1999 2000 /* Clean up fds */ 2001 close(REEXEC_CONFIG_PASS_FD); 2002 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2003 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2004 dup2(fd, STDIN_FILENO); 2005 dup2(fd, STDOUT_FILENO); 2006 if (fd > STDERR_FILENO) 2007 close(fd); 2008 } 2009 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2010 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2011 } 2012 2013 /* Executed child processes don't need these. */ 2014 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2015 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2016 2017 /* 2018 * Disable the key regeneration alarm. We will not regenerate the 2019 * key since we are no longer in a position to give it to anyone. We 2020 * will not restart on SIGHUP since it no longer makes sense. 2021 */ 2022 alarm(0); 2023 signal(SIGALRM, SIG_DFL); 2024 signal(SIGHUP, SIG_DFL); 2025 signal(SIGTERM, SIG_DFL); 2026 signal(SIGQUIT, SIG_DFL); 2027 signal(SIGCHLD, SIG_DFL); 2028 signal(SIGINT, SIG_DFL); 2029 2030 #ifdef __FreeBSD__ 2031 /* 2032 * Initialize the resolver. This may not happen automatically 2033 * before privsep chroot(). 2034 */ 2035 if ((_res.options & RES_INIT) == 0) { 2036 debug("res_init()"); 2037 res_init(); 2038 } 2039 #ifdef GSSAPI 2040 /* 2041 * Force GSS-API to parse its configuration and load any 2042 * mechanism plugins. 2043 */ 2044 { 2045 gss_OID_set mechs; 2046 OM_uint32 minor_status; 2047 gss_indicate_mechs(&minor_status, &mechs); 2048 gss_release_oid_set(&minor_status, &mechs); 2049 } 2050 #endif 2051 #endif 2052 2053 /* 2054 * Register our connection. This turns encryption off because we do 2055 * not have a key. 2056 */ 2057 packet_set_connection(sock_in, sock_out); 2058 packet_set_server(); 2059 ssh = active_state; /* XXX */ 2060 2061 check_ip_options(ssh); 2062 2063 /* Prepare the channels layer */ 2064 channel_init_channels(ssh); 2065 channel_set_af(ssh, options.address_family); 2066 process_permitopen(ssh, &options); 2067 2068 /* Set SO_KEEPALIVE if requested. */ 2069 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2070 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2071 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2072 2073 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2074 debug("ssh_remote_port failed"); 2075 cleanup_exit(255); 2076 } 2077 2078 if (options.routing_domain != NULL) 2079 set_process_rdomain(ssh, options.routing_domain); 2080 2081 /* 2082 * The rest of the code depends on the fact that 2083 * ssh_remote_ipaddr() caches the remote ip, even if 2084 * the socket goes away. 2085 */ 2086 remote_ip = ssh_remote_ipaddr(ssh); 2087 2088 #ifdef SSH_AUDIT_EVENTS 2089 audit_connection_from(remote_ip, remote_port); 2090 #endif 2091 #ifdef LIBWRAP 2092 allow_severity = options.log_facility|LOG_INFO; 2093 deny_severity = options.log_facility|LOG_WARNING; 2094 /* Check whether logins are denied from this host. */ 2095 if (packet_connection_is_on_socket()) { 2096 struct request_info req; 2097 2098 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2099 fromhost(&req); 2100 2101 if (!hosts_access(&req)) { 2102 debug("Connection refused by tcp wrapper"); 2103 refuse(&req); 2104 /* NOTREACHED */ 2105 fatal("libwrap refuse returns"); 2106 } 2107 } 2108 #endif /* LIBWRAP */ 2109 2110 rdomain = ssh_packet_rdomain_in(ssh); 2111 2112 /* Log the connection. */ 2113 laddr = get_local_ipaddr(sock_in); 2114 verbose("Connection from %s port %d on %s port %d%s%s%s", 2115 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2116 rdomain == NULL ? "" : " rdomain \"", 2117 rdomain == NULL ? "" : rdomain, 2118 rdomain == NULL ? "" : "\""); 2119 free(laddr); 2120 2121 /* 2122 * We don't want to listen forever unless the other side 2123 * successfully authenticates itself. So we set up an alarm which is 2124 * cleared after successful authentication. A limit of zero 2125 * indicates no limit. Note that we don't set the alarm in debugging 2126 * mode; it is just annoying to have the server exit just when you 2127 * are about to discover the bug. 2128 */ 2129 signal(SIGALRM, grace_alarm_handler); 2130 if (!debug_flag) 2131 alarm(options.login_grace_time); 2132 2133 sshd_exchange_identification(ssh, sock_in, sock_out); 2134 packet_set_nonblocking(); 2135 2136 /* allocate authentication context */ 2137 authctxt = xcalloc(1, sizeof(*authctxt)); 2138 2139 authctxt->loginmsg = &loginmsg; 2140 2141 /* XXX global for cleanup, access from other modules */ 2142 the_authctxt = authctxt; 2143 2144 /* Set default key authentication options */ 2145 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2146 fatal("allocation failed"); 2147 2148 /* prepare buffer to collect messages to display to user after login */ 2149 buffer_init(&loginmsg); 2150 auth_debug_reset(); 2151 2152 BLACKLIST_INIT(); 2153 2154 if (use_privsep) { 2155 if (privsep_preauth(authctxt) == 1) 2156 goto authenticated; 2157 } else if (have_agent) { 2158 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2159 error("Unable to get agent socket: %s", ssh_err(r)); 2160 have_agent = 0; 2161 } 2162 } 2163 2164 /* perform the key exchange */ 2165 /* authenticate user and start session */ 2166 do_ssh2_kex(); 2167 do_authentication2(authctxt); 2168 2169 /* 2170 * If we use privilege separation, the unprivileged child transfers 2171 * the current keystate and exits 2172 */ 2173 if (use_privsep) { 2174 mm_send_keystate(pmonitor); 2175 packet_clear_keys(); 2176 exit(0); 2177 } 2178 2179 authenticated: 2180 /* 2181 * Cancel the alarm we set to limit the time taken for 2182 * authentication. 2183 */ 2184 alarm(0); 2185 signal(SIGALRM, SIG_DFL); 2186 authctxt->authenticated = 1; 2187 if (startup_pipe != -1) { 2188 close(startup_pipe); 2189 startup_pipe = -1; 2190 } 2191 2192 #ifdef SSH_AUDIT_EVENTS 2193 audit_event(SSH_AUTH_SUCCESS); 2194 #endif 2195 2196 #ifdef GSSAPI 2197 if (options.gss_authentication) { 2198 temporarily_use_uid(authctxt->pw); 2199 ssh_gssapi_storecreds(); 2200 restore_uid(); 2201 } 2202 #endif 2203 #ifdef USE_PAM 2204 if (options.use_pam) { 2205 do_pam_setcred(1); 2206 do_pam_session(ssh); 2207 } 2208 #endif 2209 2210 /* 2211 * In privilege separation, we fork another child and prepare 2212 * file descriptor passing. 2213 */ 2214 if (use_privsep) { 2215 privsep_postauth(authctxt); 2216 /* the monitor process [priv] will not return */ 2217 } 2218 2219 packet_set_timeout(options.client_alive_interval, 2220 options.client_alive_count_max); 2221 2222 /* Try to send all our hostkeys to the client */ 2223 notify_hostkeys(ssh); 2224 2225 /* Start session. */ 2226 do_authenticated(ssh, authctxt); 2227 2228 /* The connection has been terminated. */ 2229 packet_get_bytes(&ibytes, &obytes); 2230 verbose("Transferred: sent %llu, received %llu bytes", 2231 (unsigned long long)obytes, (unsigned long long)ibytes); 2232 2233 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2234 2235 #ifdef USE_PAM 2236 if (options.use_pam) 2237 finish_pam(); 2238 #endif /* USE_PAM */ 2239 2240 #ifdef SSH_AUDIT_EVENTS 2241 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2242 #endif 2243 2244 packet_close(); 2245 2246 if (use_privsep) 2247 mm_terminate(); 2248 2249 exit(0); 2250 } 2251 2252 int 2253 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey, 2254 u_char **signature, size_t *slen, const u_char *data, size_t dlen, 2255 const char *alg, u_int flag) 2256 { 2257 int r; 2258 u_int xxx_slen, xxx_dlen = dlen; 2259 2260 if (privkey) { 2261 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2262 alg) < 0)) 2263 fatal("%s: key_sign failed", __func__); 2264 if (slen) 2265 *slen = xxx_slen; 2266 } else if (use_privsep) { 2267 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2268 alg) < 0) 2269 fatal("%s: pubkey_sign failed", __func__); 2270 if (slen) 2271 *slen = xxx_slen; 2272 } else { 2273 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2274 data, dlen, alg, datafellows)) != 0) 2275 fatal("%s: ssh_agent_sign failed: %s", 2276 __func__, ssh_err(r)); 2277 } 2278 return 0; 2279 } 2280 2281 /* SSH2 key exchange */ 2282 static void 2283 do_ssh2_kex(void) 2284 { 2285 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2286 struct kex *kex; 2287 int r; 2288 2289 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2290 options.kex_algorithms); 2291 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2292 options.ciphers); 2293 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2294 options.ciphers); 2295 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2296 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2297 2298 if (options.compression == COMP_NONE) { 2299 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2300 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2301 } 2302 2303 if (options.rekey_limit || options.rekey_interval) 2304 packet_set_rekey_limits(options.rekey_limit, 2305 options.rekey_interval); 2306 2307 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2308 list_hostkey_types()); 2309 2310 /* start key exchange */ 2311 if ((r = kex_setup(active_state, myproposal)) != 0) 2312 fatal("kex_setup: %s", ssh_err(r)); 2313 kex = active_state->kex; 2314 #ifdef WITH_OPENSSL 2315 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2316 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2317 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2318 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2319 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2320 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2321 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2322 # ifdef OPENSSL_HAS_ECC 2323 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2324 # endif 2325 #endif 2326 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2327 kex->server = 1; 2328 kex->client_version_string=client_version_string; 2329 kex->server_version_string=server_version_string; 2330 kex->load_host_public_key=&get_hostkey_public_by_type; 2331 kex->load_host_private_key=&get_hostkey_private_by_type; 2332 kex->host_key_index=&get_hostkey_index; 2333 kex->sign = sshd_hostkey_sign; 2334 2335 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 2336 2337 session_id2 = kex->session_id; 2338 session_id2_len = kex->session_id_len; 2339 2340 #ifdef DEBUG_KEXDH 2341 /* send 1st encrypted/maced/compressed message */ 2342 packet_start(SSH2_MSG_IGNORE); 2343 packet_put_cstring("markus"); 2344 packet_send(); 2345 packet_write_wait(); 2346 #endif 2347 debug("KEX done"); 2348 } 2349 2350 /* server specific fatal cleanup */ 2351 void 2352 cleanup_exit(int i) 2353 { 2354 struct ssh *ssh = active_state; /* XXX */ 2355 2356 if (the_authctxt) { 2357 do_cleanup(ssh, the_authctxt); 2358 if (use_privsep && privsep_is_preauth && 2359 pmonitor != NULL && pmonitor->m_pid > 1) { 2360 debug("Killing privsep child %d", pmonitor->m_pid); 2361 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2362 errno != ESRCH) 2363 error("%s: kill(%d): %s", __func__, 2364 pmonitor->m_pid, strerror(errno)); 2365 } 2366 } 2367 #ifdef SSH_AUDIT_EVENTS 2368 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2369 if (!use_privsep || mm_is_monitor()) 2370 audit_event(SSH_CONNECTION_ABANDON); 2371 #endif 2372 _exit(i); 2373 } 2374